That is exactly the idea.
I think you need to gain a much better understanding of how plants and soils work together. In organic soils the biology within the soil will feed the plants. It is the process of decomposition that makes nutrients available to the plants. Microbial life (mychorrizae and bacteria) break down the organic matter that is in the soil. The nutrients are held within the organic materials that are put into the soil, and as that organic matter is broken down by the micro-life plant available forms of elements are produced. It is not until this point that the plants are able to use the nutrients within the soil. Since decomposition does not happen over night, nutrients are not available immediately to the plants in that soil. Over the period of the plants life the organic matter within the soil is broken down further and further becoming available throughout the life cycle of the plants.
Lets take a quick look at mineral nutrients in hydroponic systems. In this scenario the nutrients are ideally immediately available to the plants. But this does not simply happen by putting different elements and compounds in a bottle and shipping it off, the nutrients actually must be chelated at which point they become available to the plants. This chelation process is a process of breaking down certain bonds of the compounds and forming new bonds with atoms and molecules that are easy for the plant to take in.
So we can see the requirements for plants to take in nutrients is not as simple as provide some nitrogen and the plant now has nitrogen to feed on. So now in our soil we can see we not only need to provide the necessary nutrients but the micro-life that will convert the organic materials into plant available forms. As I stated before this process does not happen over night and is not completed in the course of 3 months either. Not only that but a plant is only able to take in whatever nutrients are available near the root zone. If you have a 5 gallon pot of soil but a root zone that only is using 10% of that space for its root ball it will only be able to take up the nutrients around that 10% of the pot. As the roots grow out from there the nutrients in other parts of the pot are now available for the plant. Also not all organic materials will decompose at the same rate, some will break down slower than others, making certain nutrients available at different points in the plants life cycle. Think of long release fertilizers they depend on this fact.
You can also mix up two different soils with different profiles, one for veg and one for bloom. One will have a higher nitrogen ratio and one will be higher is phosphorus and potassium. This again keeps the steps to two mixes as opposed to one per week of the plants life. A simple transplant from the veg soil into a pot with bloom soil makes this a very simple process to provide your plants with exactly what they need at the correct time.
I could honestly go on a write a whole article about this topic, but I think this covers most of it. If you are still skeptical about the use of super soils just look around on this site at those who have used the super soil mixes with great success.
